I’ve had two opinions around quantum entanglement:

Simulation: An algorithm decides how small something should be to show it, depending on whether someone is watching or not. Just like how a video game doesn’t render anything off-screen, because there is no point and it wastes processing power.

Non-simulation: I always though it was a factor of size and being an object made from a single element.

Turns out a creature can be observed in a quantum entangled state:

In the experiment, researchers placed a tardigrade tun on a superconducting qubit and observed coupling between the qubit and the tardigrade tun via a shift in the resonance frequency of the new qubit-tardigrade system. They then entangled this joint qubit-tardigrade
system with a second superconducting qubit.
https://www.dailygrail.com/2021/12/quantum-tardigrade-scientists-observe-quantum-entanglement-in-a-multicellular-living-creature-for-the-first-time/

So, I consider this to be a strong indicator of us in a simulation, unless some scientists can explain it.